Fluidized bed apparatus

ABSTRACT

Fluid material distributing apparatus for use in a fluidized bed consists of a rotatable shaft having a longitudinal passage therein communicating with nozzle members located adjacent an outlet of the shaft. The nozzle members are tubular arms affixed to a distribution head carried by the shaft. Fluid material is, in use, conveyed, e.g. pneumatically, through the passage and discharges through the arms by virtue of centrifugal force generated by the rotation of the shaft, the material thereby being distributed within the fluidized bed.

United States Patent 1 1 1111 Hoy et al. Jan. 8, 1974 FLU I l )lZ Ep l 3El A PA3ATg s 3,412,986 11/1968 Shepherd et al 239/1323 x 1,506,2268/1924 Dick 239/245 X [75] Inventors; Herbert f Surrey; 1,613,660 1/1927Hoag 239121425 Ronald Leslie Johnson, Bletchley; 2,637,595 5/1953 Fox etal 239/244 Whalley Vowe Battcock, Surrey, all f England FOREIGN PATENTSOR APPLICATIONS 260,478 11/1926 G t B 'ta' 239/245 [73] Asslgwe Eggt ggg g z 467,506 lO/1928 eZZi'm;....7 239/245 Filedi 1971 PrimaryExaminer-M. Henson Wood, Jr.

Assistant ExaminerJohn J. Love Appl' 205-559 9 fl i 9! S Mine & Mosher[30] Foreign Application Priority Data 57] ABSTRACT Dec. 23, 1970 GreatBritain 61,032/70 I Fluid material distrlbutmg apparatus for use In aflui- 152 US. c1 239/264 239/2415 239/1310. 19 fil d9998Mofarowwbieshafl huvingalongiw- 51 Int. 01 B05b 3/02 dinal Passagetherein communicating with "Ozzie [58] Field of Search 239/226 243-245members located adjacent an outlet of the Shafl- The 239/248 246 26421415 21419 nozzle members are tubular arms affixed to a distribu-214,25 1323 tion head carried by the shaft. Fluid material is, in use,conveyed, e.g. pneumatically, through the passage and [56] ReferencesCited discharges through the arms by virtue of centrifugal forcegenerated by the rotation of the shaft, the mate- 1 582 943 SZ PATENTS239,244 X rial thereby being distributed within the nuidiz q g.

0 et a. 3,175,772 3 1965 Marshall 239 591 x 9 Claims, 3 Drawing FiguresPA-TENTED JAN 81974 SHEET 2 BF 2 FIG-2 1 .Il E D l lD DAPPABAILL Thisinvention relates to apparatus for distributing The expression fluidmaterials as used herein includes gaseous or liquid materials and/ormaterials capable of flow in a manner similar to or the same as that ofa gas or liquid, e.g. particulate or pulverulent materials.

In fluid bed processes it is essential that there should be uniformdispersal or distribution of material for maximum process efficiency.For example, in the field of fluidised bed combustion, it is necessarythat fuel feed to the bed should be dispersed uniformly throughout thebed in a horizontal plane across the bed as low and as rapidly aspossible because the air distribution cannot depart greatly from beinguniform if satisfactory fluidization is to be maintained. It isdesirable that the amount of fuel available to the air'fibiiid' besuclifhat complete combustion is obtained with the minimum of excess airat all points on the surface of the bed.

An object of the invention is to provide apparatus for distributingfluid materials in a uniform pattern.

According to the invention apparatus for distributing fluid materials iga fluidized bed includes a rotatable shaft provided with an internalpassage formed longitudinally thereof, an inlet and an outlet for fluidmaterial in the shaft communicating with said passage, and a number ofnozzle members associated with the shaft and located at or towards oneend thereof in communication with said outlet.

Preferably the or each nozzle member is in the form of a tubular armextending from the shaft and having one or more apertures formed thereinfor the discharge of fluid material. The or each arm may extend radiallyof the shaft perpendicularly to the axis thereof. Alternatively, the oreach arm may radiate from the axis of the shaft at an angle thereto. Theaperture may be located at the extremity of the arm remote from theshaft. Additional apertures may be located at points along the length ofthe arm. Alternatively the aperture may be a horizontal slot extendinglongitudinally of the arm.

Conveniently the or each arm is attached to the shaft through the agencyof a distribution head secured to the end of the shaft. A furtherrelatively upper distribution head may be arranged superjacent theaforementioned head, the further head having attached radially theretonozzle members of the form hereinbefore described. The further head maybe attached to the first mentioned head and in this case a relativelyinner conduit is provided which extends co-axially within the rotatableshaft to define an annular space therebetween. The inner conduit istubular and has an inlet and an outlet for fluid material, the outletcommunicating with said further head. Alternatively, the further headmay be separate from the first mentioned head and the inner conduit maybe independently rotatable within the rotatable shaft.

The tubular arms attached to the relatively upper head may convenientlybe of shorter length than the tubular arms of the first mentioned head.Where the apparatus is to be utilised in high temperature conditions thearm may be provided with heat insulative material to minimize heattransfer through the arm to fluid material which in use flowstherethrough. The heat insulative material may be situated between thearm and an outer casing therefor, the casing being made from a materialselected for its resistance to abrasion and corrosion at temperaturesapproaching that of the fluidised bed. The casing may be cylindrical ormay be suitably profiled to minimize resistance to movement through thefluidized material, to effect movement of the fluidized material and/orto minimize abrasion of the casing. For exarnple, the profile may be ofaerofoil section or elliptical or substantially elliptical.Alternatively, each arm may be provided with a casing defining a coolingspace between it and the arm; in use a fluid cooling medium e.g. wateror gas is passed through the space to cool the arm and thus reduce therate at which heat is transferred to the material flowing through thearm. The cooling medium may be conveyed to the arm through a gland and asuitable duct in the rotatable shaft and returned in a similar manneror, where the process allows may be dischagd into the fluidized bed.Again, the casing may be profiled in a smri'iiififi'ii ner as aforesaid.In the absence of a casing the arm itself may be similarly profiled.

Conveniently drive means are provided for rotating the rotatable shaftand further independent drive means are provided for the inner conduitwhen this is to be rotated independently. A cooling medium may be passedthrough suitable ducts to cool the rotatable shaft and the medium may besupplied to annular spaces round the shaft to prevent granular materialgetting into seals or bearings. The drive means may be of anyconventional form but may be provided with torque limiting features.

By way of example only, apparatus for distributing fluid materials in afluidized bed according to the invention is described below withreference to the accompanying drawings in which:

FIG. 1 is a cross-sectional view;

FIG. 2 is a cross-sectional view of an alternative embodiment of adetail shown in FIG. 1; and

FIG. 3 is a plan view of the detail shown in FIG. 2.

Referring to FIG. I, apparatus for distributing fluid materials includesa rotatable shaft 2 having a longitudinal passage 4 formed therein. Theshaft 2 has an inlet 6 at its lower end 8 communicating with a fixedinlet conduit 10, and an outlet 12 at its upper end 14, whichcommunicates with a distribution head 16, the head 16 being detachablysecured to a flange 18 formed on the upper end 14 of the shaft.

The shaft 2 is mounted for rotation in a casing assembly indicatedgenerally by the reference numeral 20. The assembly 20 includes threeparts, a lower part 22, an intermediate part 24 and an upper part 26.The shaft 2 is supported at its lower end in lower part 22 by a bearing28, subjacent to which is a seal 30. The inlet conduit 10 extends intothe part 22 and communicates directly with the inlet 6 of the shaft 2 todefine an annular space 32 below the seal 30. The space 32 is providedfor the ingress of a high pressure gas medium at such pressure as toassist in preventing extraneous matter from entering the space from duct10. The intermediate part 24 is secured to the lower part 22 andconstitutes a gear box containing a gear train including a driven pinion34 keyed to the shaft 2. The seal 30 prevents contamination of the geartrain and the bearing 28 by extraneous matter, for example, fluidmaterial flowing through the shaft 2. The upper part 26 is fixed to theintermediate part 24 and is adapted for securement to a base support 36of, for example, a fluidized combustor (not shown). The part 26 housesan upper bearing 38 for supporting the shaft 2 and an upper seal 40superjacent the bearing 38. The seal 40 prevents contamination of thegearbox and bearing 38 by extraneous matter, e.g. material which mayescape from the combustor located thereabove. The shaft 2 extends beyondthe part 26 terminating at its upper end 14 in flange 18 which carriesthe distribution head 16.

The head 16 is substantially cylindrical and has two radial ports 42, 44each having an arm 46, 48 respectively. The arms 46, 48 extend radiallyof the head 16 and are secured in the ports 42, 44, the arms beingtubular and having an outer casing 43 of wear resistant material and anintermediate layer 45 of heat insulative material extending oversubstantially the whole surface of the arms 46, 48. The arms 46, 48 havedischarge apertures 50, 52 at their free ends remote from the head 16.

The head 16 has a central bore 54 through which extends a fixed innertubular conduit 56, the conduit 56 extending downwardly through therotatable shaft 2 and communicating at its lower end 58 with an inputduct 60. The inner conduit 56 further extends upwardly to communicatewith an upper head 62 through a bore 64 formed therein; a seal 63 isarranged outside the conduit 56 within the bore 64 of the upper head 62.

The upper head 62 has two radial outlets 65, 66 having arms 68, 70respectively, and is secured to the head 16 for rotation therewith. Eacharm 68, 70 is tubular and has an outer casing 71 of wear resistantmaterial and an intermediate layer of heat insulative material 73extending over substantially the whole outer surface of the arms 68, 70,which are provided with discharge apertures 72, 74 respectively, attheir free ends remote from the head 62. In this particular embodiment,the arms 68, 70 are shorter than the arms 46, 48.

FIGS. 2 and 3 show an alternative form of arm to that shown in FIG. 1.Each arm 75 is tapered and has at its smallest end 76 an aperture 78.Additionally the arm is provided with an elongate slot 80 extendinglongitudinally thereof; in use the slot 80 would be on the trailing sideof the arm 75, such that material issuing through the slot 80 isdistributed in the wake of the arm. Although in this embodiment the slot80 is continuous along the length of each arm 75, it is envisaged that aseries of slots 80 of shorter length could be provided.

If, for example, the apparatus of the invention is utilized in afluidized combustorflqtshown) for the distribution of fuel therein theapparatus is affixed to the body 36 of the combustor as shown such thatthe heads 16 and 62 are located above a gas-permeable support grid 82 asshown in FIG. 1. The apparatus operates as follows:

The shaft 2 is rotated through the gear train in part 24 by drive means(not shown) and fuel, for example coal in particulate or pulverulentform, is pneumatically conveyed through the inlet conduit to the inlet 6of the rotatable shaft 2. The coal passes through the passage 4 until itreaches the head 16 whence the coal is transported through the arms 46,48 to be discharged therefrom through the discharge apertures 50, 52.Simultaneously, coal feed is introduced to the: distributor conduit 56via the input duct 60 and the lower end 58 of the shaft. The coal feedis pneumatically transported up through the conduit 56 until it entersthe head 62 from which it is discharged into the fluid bed throughdischarges apertures 72, 74 of arms 68, 70. The angular velocity of thearms is preferably such that the time for one revolution would be lessthan the height of the fluidized bed divided by the fluidizing velocityof the s d zisst is i m mslqyai t fl isfiz q It is to be understood thatthe invention is not limited to the specific embodiments and thatvariations of the apparatus shown lie within the scope of the invention.For example, such variations include the exclusion of the inner conduit56 such that the material feed is common to all the arms, 46, 48, 68 and70. Alternatively each arm may be in communication with a separate ductwithin the shaft 2, each duct being fed separately so that the rate ofmaterial feed to each arm may be controlled separately. Additionally itis envisaged that the inner conduit 56 may be rotatable separately fromthe shaft 2, the head 62 being secured to shaft 56 and separate from thehead 16. The distribution of material could then be effected by theupper head 62 and tubes 68, 70, independently of the shaft 2; similarlythe shaft 2 and hencethe head 16 could be rotated independently of theconduit 56. Suitable bearings, seals, blands and a driving mechanismwould be provided for the inner conduit 56 for independently rotatingthe head 62.

As a further alternative the conduit 56, in this specific embodimentdescribed above with reference to the drawings, may be secured to thehead 62 so as to be rotatable therewith and with the head 16, in whichcase the input duct would be fixed and a sealing arrangement similar tothat for shaft 2 would be employed.

Examples of fluid materials which may be distributed by the apparatus ofthe invention are particulate solid fuel, liquid fuel, gaseous fuel,mixtures of fuel and oxygen-containing gas or reactants such asparticulate limestone, or inert particulate material.

It is to be understood that fluid materials to be distributed by theapparatus may be conveyed therethrough by any suitable fluid transportmedium e.g. air, water, oil or gas.

We claim:

1. In a fluidized bed combuster comprising a body and a fluid materialdistributing apparatus, the improvement which comprises employing afluid material distributing apparatus comprising a rotatable shaft,

a passage formed longitudinally within the shaft,

fluid material inlet means and fluid material outlet means in the shaft,said inlet and outlet means communicating with the passage, and

a number of tubular nozzle members each in communication with the outletmeans having an abrasion and corrosion resistant casing located abouteach tubular nozzle member and a thermal insulative medium situatedinterjacent each tubular nozzle member and its associated casing.

2. The fluidized bed combuster according to claim 1 including a firstdistribution head attached to the shaft, the head being located adjacentand in communication with said outlet means, at least one of saidtubular nozzle members being attached to said head.

3. The fluidized bed combuster according to claim 2 including a seconddistribution head located superjacent the first distribution head, atleast one of said tubular nozzle members being attached to the secondhead.

7. The fluidized bed combuster according to claim 1 wherein each tubularnozzle member is provided with discharge means.

8. The fluidized bed combuster according to claim 6 wherein thedischarge means is an aperture in the nozzle member located at the faceend thereof.

9. The fluidized bed combuster according to claim 6 wherein thedischarge means is elongate and extends longitudinally of the tubularnozzle member.

1. In a fluidized bed combuster comprising a body and a fluid materialdistributing apparatus, the improvement which comprises employing afluid material distributing apparatus comprising a rotatable shaft, apassage formed longitudinally within the shaft, fluid material inletmeans and fluid material outlet means in the shaft, said inlet andoutlet means communicating with the passage, and a number of tubularnozzle members each in communication with the outlet means having anabrasion and corrosion resistant casing located about each tubularnozzle member and a thermal insulative medium situated interjacent eachtubular nozzle member and its associated casing.
 2. The fluidized bedcombuster according to claim 1 including a first distribution headattached to the shaft, the head being located adjacent and incommunication with said outlet means, at least one of said tubularnozzle members being attached to said head.
 3. The fluidized bedcombuster according to claim 2 including a second distribution headlocated superjacent the first distribution head, at least one of saidtubular nozzle members being attached to the second head.
 4. Thefluidized bed combustor according to claim 3 wherein the seconddistribution head is attached to the first distribution head.
 5. Thefluidized bed combuster according to claim 4 including a fixed feedconduit extending coxially within the passage of the shaft, a fluidmaterial inlet means and outlet means in the conduit, the outlet meanscommunicating with the second distribution head.
 6. The fluidized bedcombuster according to claim 2 wherein the second distribution head isattached to and communicates with the first distribution head.
 7. Thefluidized bed combuster according to claim 1 wherein each tubular nozzlemember is provided with discharge means.
 8. The fluidized bed combusteraccording to claim 6 wherein the discharge means is an aperture in thenozzle member located at the face end thereof.
 9. The fluidized bedcombuster according to claim 6 wherein the discharge means is elongateand extends longitudinally of the tubular nozzlE member.